Fiberplates made of polyamines or polyamine-containing aminoplast resins as binding agents

ABSTRACT

A process for producing fiberboard panels includes 
     I. gluing cellulosic fibers with an aqueous glue solution 
     and adjusting the moisture content of the cellulosic fibers and/or the water content of the glue such that the moisture content of the glued cellulosic fibers is not more than 150%; and 
     II. compressing the glued cellulosic fibers produced in step (I) at elevated temperature to fiberboard panels.

This application is a 371 of PCT/EP00/05858 filed Jun. 23, 2000.

The present invention relates to a process for producing fiberboardpanels by

I. gluing cellulosic fibers with an aqueous glue solution comprising

a) for a glue solution (a), an aliphatic polyamine having at least 3groups selected from the group consisting of primary and secondary aminogroups, having a weight average molar weight of from 600 to 1000000g/mol, and being substantially free from other functional groups apartfrom tertiary amino groups (polyamine P); or

b) for a glue solution (b), a mixture of a polyamine P and an aminoresin (b) synthesized from

b1) formaldehyde;

b2) a compound (b2) selected from the group consisting of urea andmelamine, the ratio of the amino groups of compound (b2) to formaldehydebeing from 0.4:1 to 3:1;

b3) and, if desired, up to 0.2 mol per mole formaldehyde of anothercompound, (b3), capable of reacting with formaldehyde in apolycondensation reaction;

b4) and, if desired, up to 0.2 mol per mole amino groups of compound(b2) of another compound, (b4), capable of reacting with amino groups ina polycondensation reaction; or

c) for a glue solution (c), an amino resin (c) synthesized from

c1) formaldehyde;

c2) a compound (c2) selected from the group consisting of urea andmelamine, the ratio of the amino groups of compound (c2) to formaldehydebeing from 0.3:1 to 3.0:1;

c3) a polyamine P, the molar ratio of the sum of primary, secondary, andtertiary amino groups of polyamine P to the sum of primary amino groupsof compound (c2) being from 0.0005:1 to 2:1;

c4) and, if desired, up to 0.2 mol per mole formaldehyde of anothercompound, (c4), capable of reacting with formaldehyde in apolycuadensation reaction; and

c5) if desired, up to 0.2 mol per mole amino groups of compound (c2) ofanother compound, (c5), capable of reacting with amino groups in apolycondensation reaction;

and adjusting the moisture content of the cellulosic fibers and/or thewater content of the glue such that the moisture content of the gluedcellulosic fibers is not more than 150%; and

II. compressing the glued cellulosic fibers produced in step (I) atelevated temperature to fiberboard panels.

The invention further relates to fiberboard panels produced by thisprocess and to the glue solution (c).

The production of fiberboard panels is common knowledge and isdescribed, for example, in the monograph entitled “MDF—MitteldichteFaserplatten” by Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-VerlagWeinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen (DE). Fiberboardpanels may be produced, for example, by gluing cellulosic fibers withamino resins and then compressing them at elevated temperature. Adisadvantage of the fiberboard panels produced in this way is thatrelatively large quantities of glue are required in order to producepanels having good mechanical properties, particularly a good transversetensile strength. Moreover, in the predominant number of plants, thecellulosic fibers used must be predried after gluing, since the fibersglued with the conventional binders must have a moisture content of onlyup to 12% if problems are to be avoided during the production of thepanels.

Apart from the fact that they are both woodbase materials, chipboard andfiberboard have little in common. This relates first to the performanceproperties. The aforementioned monograph by Deppe/Ernst refersexplicitly to this, for example, concerning comparison of theperformance properties of the two materials (cf. paragraph 1 of section6.3 and paragraph 1 of chapter 7, “IMDF and chipboard panels differ inperformance, in some cases very considerably”). From the aforementionedmonograph it is also known that the manufacturing technology of each isalso different and that the raw wood material used has differentproperties and is differently prepared. For example, at the beginning ofsection 4.1 of the monograph, there is the following note: “In terms ofthe preparation of the raw material, critical differences exist betweenchipboard and MDF technologies”. And at the beginning of section 4.2 itgoes on to say: “Fiber material requires, for its drying, technicalequipment which differs fundamentally from the types which are common inthe chipboard industry”. It is consequently no surprise to the skilledworker that binders for the production of chipboard panels and MDF arenot suitable in the same way. Whereas resins comprisingpolyethyleneimine as sole binder give high-grade MDF (cf. examples 1 to6) it is virtually impossible to product chipboard panels from the sameresin (cf. comparative example 3). The conclusion the skilled workerdraws from this is that experience gained in the production andproperties of chipboard panels cannot be transferred to MDF.

For the sake of comprehensiveness it should nevertheless be mentionedthat DE-A-4308089 discloses producing chipboard panels with a bindercomprising an aqueous solution of a polyamine, from 0.01 to 0.25 molsugar per mole of amino groups, and from 0.01 to 0.25 mol, per moleamino groups, of dicarboxylic acid derivatives, aldehydes or epoxides.

U.S. Pat. No. 3,642,671 proposes producing chipboard panels byresinating wooden chips with a resin comprising polyethyleneimine anddextrose or other dextroselike compounds and compressing them tochipboard panels under elevated temperature and pressure.

Journal of Applied Polymer Science 49 (1993) 229-245 describes howchipboard panels bound with modified urea-formaldehyde resins are foundmore resistant and more stable in a hot, moist environment than thoseproduced using customary amino resins. Proposed modifiers are lowmolecular mass polyamines or their hydrochlorides or polyalkylene oxidediamines.

USSR patents 501890, 612819, 844273 and der JP-A S57-95399 disclose MDFproduced by the wet process. In this process an aqueous suspension ofcellulosic fibers, a polyethyleneimine, and other auxiliaries, with awater fraction of more than 95%, is poured out and predried to matshaving water contents of more than 60% (corresponding to fiber moisturecontents of 150% based on bone dry fiber). These mats are subsequentlycompressed to hardboard panels.

The furniture industry has a particular requirement for fiberboardpanels which

are highly compacted, so that they have good mechanical properties,

are from about 6 to 40 mm thick, so that they can be used to producefurniture side pieces or doors, and

have a smooth surface on both sides. Panels of this kind are referred toas S2S (smooth two sides) panels (cf. Ullmann's Encyclopedia ofIndustrial Chemistry, 1996 VCH Verlagsgesellschaft, Vol. A 28, section2.3.2.1, page 336)

For economic reasons, fiberboard panels having this profile ofproperties are not produced by the wet process. That process can only beused economically to produce panels of high density with a thickness ofup to 5 mm (cf. Ullmann's Encyclopedia of Industrial Chemistry, 1996 VCHVerlagsgesellschaft, Vol. A 28, section 2.3.2.2, page 337, column 1,paragraph 1). The reason for this is that with this process it is notpossible using economic pressing conditions to achieve adequatecompaction and curing of the middle of the panel. Moreover, the panelsproduced by the wet process have a rough surface on one side. This is aconsequence of the production process: to remove the higher waterfraction it is necessary when compressing the fiber molding for onepress tool to have a screen structure. The pattern of this screenstructure is embossed on one of the sides of the fiber panel. Panels ofthis kind are known as S1S (smooth one side) panels. This uneven surfaceis often troublesome in the course of further processing, when coatingwith decorative paper, for example.

A further disadvantage of the wet process is that it produces largeamounts of contaminated wastewater.

It is an object of the present invention to provide fiberboard panelswhich do not have the abovementioned disadvantages and which arecharacterized in particular by the following properties: a thickness offrom 6 to 40 mm, a density of from 500 to 900 kg/m³, and 2 smoothsurfaces.

We have found that this object is achieved by the fiberboard panelsdefined at the outset, by processes for producing them, and by gluesolutions from which such panels can be produced.

Suitable cellulosic fibers include those commonly used to produce MDF.Raw materials of this kind are described, for example, in“MDF—Mitteldichte Faserplatten”, Hans-Joachim Deppe, Kurt Ernst, 1996,DRW-Verlag Weinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen,chapter 2, pages 25 ff. Suitable fibers are therefore those of annualplants, wastepaper fiber material, and—preferably—wood fibers.

The wood fibers are usually produced by hydrothermal pulping ofwoodchips, for example, by treating them with steam and then defiberingthem using cutting tools (cf. op. cit. section 4.1).

The wood fibers thus obtained normally have an average length of from0.2 to 5 mm, an average diameter of from 10 to 75 μm, and an averageslenderness of from 40 to 120, the slenderness being calculated from theratio of length to diameter. These parameters for characterizing thewood fibers are widely known and are described, for example, in“Werkstoffe aus Holz”, authors' collective, VEB Fachbuchverlag Leipzig1975 section 4.2.1.1.

Suitable binders comprise the glue solutions (a), (b) or (c).

The glue solution (a) comprises an aqueous solution of an aliphaticpolyamine having at least 3 functional groups selected from the groupconsisting of primary and secondary amino groups, having a weightaverage molar weight of from 600 to 1000000 g/mol, and beingsubstantially free from other functional groups apart from tertiaryamino groups (polyamine P).

Such solutions normally have a polyamine P solids content of from 20 to80% by weight. The solids content of this solution, like that of resinsolutions (b) and (c), is normally determined by pouring out a definedamount by weight (about 2 g) of the corresponding solution onto a metaldrying plate and drying it in a drying oven at 120° C. for 2 hours. Thesolids content is determined by differential weighing.

As polyamine (P) it is preferred to use polyethyleneimine orpolyvinylamine. The polyethyleneimine preferably has a weight-averagemolar weight of from 800 to 100000 and the polyvinylamine one of from5000 to 200000.

Suitable binders further include glue solutions (b). These solutionscomprise as cocomponents alongside water polyamine (P) and an aminoresin (b) synthesized from

b1) formaldehyde;

b2) a compound (b2) selected from the group consisting of urea andmelamine, the ratio of the amino groups of compound (b2) to formaldehydebeing from 0.4:1 to 3:1; and

b3) if desired, up to 0.2 mol per mole formaldehyde of another compound,(b3), capable of reacting with formaldehyde in a polycondensationreaction;

b4) and, if desired, up to 0.2 mol per mole amino groups of compound(b2) of another compound, (b4), capable of reacting with amino groups ina polycondensation reaction.

Glue resins (b) of this kind are widely known and are described, forexample, in Ullmann's Encyclopedia of Industrial Chemistry, 1996 VCHVerlagsgesellschaft, Vol. A 2, chapter “Amino Resins”, page 115 ff.

The compounds (b3) comprise, for example, guanidines, thiourea or alkalimetal hydrogen sulfite or alkali metal sulfite.

The compounds (b4) comprise, for example, carboxylic anhydrides,preferably C₁ to C₁₀ monocarboxylic or dicarboxylic anhydrides, organichalogen compounds such as C₁ to C₁₀ alkyl halides, isocyanates such asare widely known for preparing polyurethanes, e.g., hexamethylenediisocyanate, aldehydes, especially aliphatic C₁ to C₁₀ monoaldehydes ordialdehydes such as succinaldehyde or acetaldehyde, chlorohydrins,especially epichlorohydrin, or epoxides derived from thesechlorohydrins.

In the glue solution (b) the ratio of polyamine (P) to amino resin (b)is usually from 0.002:1 to 100:1, preferably from 0.01:1 to 5:1.

Normally, glue solutions (b.) having a solids content of from 40 to 70%are used.

The glue solutions (c) comprise amino resins (c) synthesized from:

c1) formaldehyde;

c2) a compound (c2) selected from the group consisting of urea andmelamine, the ratio of the amino groups of compound (c2) to formaldehydebeing from 0.3:1 to 3.0:1;

c3) a polyamine P, the molar ratio of the sum of primary and secondaryamino groups of polyamine P to the sum of primary, secondary, andtertiary amino groups of compound (c2) being from 0.0005:1 to 2:1;

c4) if desired, up to 0.2 mol per mole formaldehyde of another compound,(c4), capable of reacting with formaldehyde in a polycondensationreaction; and

c5) and, if desired, up to 0.2 mol per mole amino groups of compound(c2) of another compound, (c5), capable of reacting with amino groups ina polycondensation reaction.

Suitable compounds (c4) are the same as compounds (b3), suitablecompounds (c5) the same as compounds (b4).

Apart from the additional use of a polyamine (P), the amino resins (c)are basically prepared exactly the same as the amino resins (b).

The procedure here generally involves

in step 1, reacting an aqueous solution of

formaldehyde;

amounts of compound (c2) such that the ratio of the amino groups ofcompound (c2) to formaldehyde is from 0.1:1 to 2.0:1;

amounts of polyamine (P) such that the molar ratio of the sum of theprimary, secondaren and tertiary amino groups of polyamine P to the sumof the primary amino groups of compound (c2) is from 0.0005:1 to 2:1;

if desired, up to 0.2 mol per mole formaldehyde of another compound(c4); and

if desired, in amounts up to 0.2 mol per mole amino groups the compound(c5);

at a pH of from 2.5 to 8.5, preferably from 4.0 to 6.5, and atemperature of from 50 to 100° C. until the solution has a viscosity offrom 10 to 2000 mPas, and

in step 2, where necessary, raising the pH to from 6 to 9 and, wherenecessary, adding urea in amounts such as to give the desired molarratio of components (c1), (c2), (c3) and (c4) in the end product, andcontinuing to react the reaction mixture at a temperature of from 20 to100° C. until the solution has a viscosity of from 10 to 2000 mPas.

The viscosity figures relate to samples measured at 20° C. and adjustedto a solids content of 40% by weight prior to measurement.

Where the solids content of the resin solution (c) thus prepared islower than is desired, it is possible to raise the solids content tolevels of from 50 to 80% by distillative removal of water, preferablyunder reduced pressure, e.g., at pressures of from 1 to 10 mbar.

The glue solutions (a), (b) and (c) may further comprise customaryauxiliaries such as water repellents, e.g., paraffins or woodpreservatives. Additionally, a curing agent, e.g., a carboxylic acidsuch as formic acid or an ammonium salt, may be added to the gluesolutions immediately before their processing in order to shorten thecure times.

The glue solutions (a), (b) and (c) are applied to the cellulosic fibersby conventional methods (cf. “MDF—Mitteldichte Faserplatten”,Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-Verlag Weinbrenner GmbH & Co.,70771 Leinfelden-Echterdingen (DE), section 4.3, pages 81ff.).

A procedure commonly adopted here is to glue cellulosic fibers with amoisture content of from 0 to 120% in a blowline, i.e., by swirling thefibers in a stream of air or steam and spraying in the glue solution orperforming gluing by mixing fibers and glue solution in an open panmixer. The moisture content is defined as the ratio of the difference ofthe actual weight of the wood and the corresponding weight of bone dry(i.e., absolutely dry) fibers to the weight of bone dry fibers. Theweight of the bone dry fibers is determined by drying a defined amountof fibers in a drying oven at 105° C. for 16 hours.

For gluing, the glue solution is used in amounts such that for 100 g ofbone dry fibers there are

for glue solution (a) from 0.2 to 5 g

for glue solution (b) from 0.5 to 15 g of glue equivalents (b),calculated as follows:

glue equivalents (b)=M(b)+10×M(P)

 where

M(b) denotes the amount of amino resin (b) required to prepare a definedamount of glue solution (b); and

M(P) denotes the amount of polyamine (P) required to prepare a definedamount of glue solution (b)

for glue solution (c) from 1 to 20 g of glue equivalents (c), calculatedas follows:

glue equivalents (c)=M(c1)+M(c2) +10×M(c3)

 where

M(c1) denotes the amount of formaldehyde required to prepare a definedamount of resin solution (c);

M(c2) denotes the amount of compound (c2) for the preparation; and

M(c3) denotes the amount of compound (c3) required to prepare a definedamount of glue solution (c3)

of the corresponding glue solution (a), (b) or (c), based on the solidscontent.

The amount of glue solution or its solids content and the solids contentof the cellulosic fibers are chosen so that the moisture content of theglued cellulosic fibers is not more than 150%, preferably from 2 to120%.

The glued cellulosic fibers are then compressed to fiberboard panels bya customary method. For this purpose, a fiber mat is produced byscattering the glued cellulosic fibers onto a support and said mat iscompressed at temperatures of from 80 to 250° C. under pressures of from5 to 50 bar to fiberboard panels (cf. op. cit. section 4.5, pages 93ff).

The glued cellulosic fibers are preferably scattered to give fiber matsof a thickness such that hot compression results in fiberboard panelshaving a density of from 500 to 900 kg/m³ and a thickness of from 6 to40 mm, preferably from 10 to 25 mm. The press times required for thisare usually from 4 to 20 seconds per mm thickness of the resultantfiberboard panel.

In order to produce fiberboard panels having smooth surfaces, suitablepress tools are those having smooth surfaces; e.g., 2 polished steelbelts of which one acts as a support for the fiber mat, or a combinationof a polished steel belt support and a polished steel roller runningover it, or a combination of two or more polished steel rollers.

The resulting fiberboard panels may be processed further in thecustomary manner and are especially suitable for producing furnitureparts.

EXPERIMENTAL SECTION

Fiberboard panels were produced from different binders. The binders usedwere aqueous solutions of different polyvinylamines (PVAm) (MW=approx.1000, 30000, 200000) and different polyethyleneimines (PEI) (MW=approx.800, 2500, 5000). The properties and precise production conditions maybe found in table 1.

TABLE 1 Example 1 2 3 4 5 6 7 8 1 (C) 2 (C) Binder PVAm PVAm PVAm PVAmPEI PEI a) b) UF resin UF resin MW [daltons] 1000 11500 11500 11500200000 2500 5000 — — commercially customary pH 12-13 12-13 12-13 7 12-1312-13 12-13 9 9 9 Fiber moisture 12 12 20 20 20 12 12 12 12 20 content[%] Gluing [%] 1.25 1.25 1.25 1.25 1.25 1.25 1.25 3.5 3.5 3.5 Transversetensile 1.17 0.99 1.37 1.30 1.03 0.64 1.18 1.12 0.46 no strength [N/mm²]panels Swelling [%] 71.2 59.8 47.0 28.0 40.2 85.3 66.9 57.2 80.1 a)Blend of a commercial UF resin with PEI (MW = 2500) in a ratio of 90:10(based on solid resin) b) Glue solution prepared according to claim 6from urea, formaldehyde, and polyethyleneimine (PEI): Ratio of ureaamino groups to formaldehyde 0.8:1 Molar ratio of sum of amino groups ofpolyethyleneimine to sum of amino groups of urea = 0.2:1

COMPARATIVE EXAMPLE 3: Production of Chipboard Panels with PEI MW=5000

Problem: Panel Remains Sticking to the Press Stage; Torn During Removal

Although it was possible to obtain panels when pressing was carried outusing release paper, the panels had a low transverse tensile strength(0.4 N/mm²). In swelling tests, the test specimens fell apart.

PVAm and PEI exhibit the following advantages over conventional UFresin:

reduced glue consumption coupled with better transverse tensile strengthand similar or better swelling figures

greater moisture tolerance; i.e., in contrast to the case with UV resin,panels can be obtained even at high fiber moisture contents (20%)

We claim:
 1. A process for producing a fiberboard panel by I. gluingcellulosic fibers with an aqueous glue solution comprising a) for a gluesolution (a), an aliphatic polyamine having at least 3 groups selectedfrom the group consisting of primary and secondary amino groups, havinga weight average molar weight of from 600 to 1000000 g/mol, and beingsubstantially free from other functional groups apart from tertiaryamino groups (polyamine P); or b) for a glue solution (b), a mixture ofa polyamine P and an amino resin (b) synthesized from b1) formaldehyde;b2) a compound (b2) selected from the group consisting of urea andmelamine, the ratio of the amino groups of compound (b2) to formaldehydebeing from 0.4:1 to 3:1; b3) and, if desired, up to 0.2 mol per moleformaldehyde of another compound, (b3), capable of reacting withformaldehyde in a polycondensation reaction; b4) and, if desired, up to0.2 mol per mole amino groups of compound (b2) of another compound,(b4), capable of reacting with amino groups in a polycondensationreaction; or c) for a glue solution (c), an amino resin (c) synthesizedfrom c1) formaldehyde; c2) a compound (c2) selected from the groupconsisting of urea and melamine, the ratio of the amino groups ofcompound (c2) to formaldehyde being from 0.3:1 to 3.0:1; c3) a polyamineP, the molar ratio of the sum of primary, secondary, and tertiary aminogroups of polyamine P to the sum of primary amino groups of compound(c2) being from 0.0005:1 to 2:1; c4) and, if desired, up to 0.2 mol permole formaldehyde of another compound, (c4), capable of reacting withformaldehyde in a polycondensation reaction; c5) and, if desired, up to0.2 mol per mole amino groups of compound (c2) of another compound,(c5), capable of reacting with amino groups in a polycondensationreaction; and adjusting the moisture content of the cellulosic fibersand/or the water content of the glue such that the moisture content ofthe resinated cellulosic fibers is not more than 150%; and II.compressing the glued cellulosic fibers produced in step (I) at elevatedtemperature to a fiberboard panel.
 2. A process as claimed in claim 1,wherein the glue solution is used in amounts such that per 100 g of bonedry cellulosic fibers there are for glue solution (a) from 0.2 to 5 gfor glue solution (b) from 0.5 to 15 g of glue equivalents (b),calculated as follows: glue equivalents (b)=M(b)+10×M(P)  where M(b)denotes the amount of amino resin (b) required to prepare a definedamount of glue solution (b); and M(P) denotes the amount of polyamine(P) required to prepare a defined amount of glue solution (b) for resinsolution (c) from 1 to 20 g of glue equivalents (c), calculated asfollows: glue equivalents (c)=M(c1)+M(c2) +10×M(c3)  where M(c1) denotesthe amount of formaldehyde required to prepare a defined amount of gluesolution (c); M(c2) denotes the amount of compound (c2) for thepreparation; and M(c3) denotes the amount of compound (c3) required toprepare a defined amount of glue solution (c3) of the corresponding gluesolution (a), (b) or (c), based on the solids content.
 3. A process asclaimed in claim 1, wherein the polyamine (P) comprisespolyethyleneimine or polyvinylamine.
 4. A process as claimed in claim 3,wherein the polyethyleneimine has a weight average molar weight of from800 to 100000 and the polyvinylamine has one of from 5000 to
 200000. 5.A process as claimed in claim 1, wherein the ratio of polyamine (P) toamino resin (b) in the glue solution (b) is from 0.002:1 to 100:1.
 6. Aprocess as claimed in claim 1, wherein an amino resin (c) is used whichis synthesized from c1) formaldehyde; c2) a compound (c2) selected fromthe group consisting of urea and melamine, the ratio of the amino groupsof compound (c2) to formaldehyde being from 0.3:1 to 3:1; c3) apolyamine P, the molar ratio of the sum of primary, secondary, andtertiary amino groups of polyamine P to the sum of primary amino groupsof compound (c2) being from 0.0005:1 to 2:1; c4) if desired, up to 0.2mol per mole formaldehyde of another compound, (c4), capable of reactingwith formaldehyde in a polycondensation reaction; and c5) if desired, upto 0.2 mol per mole amino groups of compound (c2) of another compound,(c5), capable of reacting with amino groups in a polycondensationreaction; and is obtainable by in step 1, reacting an aqueous solutionof formaldehyde; amounts of compound (c2) such that the ratio of theamino groups of compound (c2) to formaldehyde is from 0.1:1 to 2.0:1;amounts of polyamine P such that the molar ratio of the sum of theprimary, secondary and tertiary amino groups of polyamine P to the sumof the primary amino groups of compound (c2) is from 0.0005:1 to 2:1;and if desired, up to 0.2 mol per mole formaldehyde of another compound(c4), if desired, in amounts up to 0.2 mol per mole amino groups ofcompound (c2), another compound (c5) at a pH of from 2.5 to 8.5 and atemperature of from 50 to 100° C. until the solution has a viscosity offrom 10 to 2000 mPas (measured at 20° C. on a solution having a solidscontent of 40%), and in step 2, where necessary, raising the pH to from6 to 9 and, where necessary, adding urea in amounts such as to give thedesired molar ratio of components (c1), (c2), (c3) and (c4) in the endproduct, and continuing to react the reaction mixture at a temperatureof from 20 to 100° C. until the solution has a viscosity of from 10 to2000 mPas (measured at 20° C. on a solution having a solids content of40%).
 7. A process as claimed in claim 1, wherein said cellulosic fiberscomprise wood fibers, fibers from annual plants or wastepaper fibermaterial.
 8. A process as claimed in claim 7, wherein said wood fibersare those obtainable by hydrothermally pulping woodchips and thendefibering them.
 9. A process as claimed in claim 8, wherein said woodfibers have an average length of from 0.2 to 5 mm, an average diameterof from 10 to 75 μm, and an average slenderness of from 40 to
 120. 10. Aprocess as claimed in claim 1, wherein gluing is conducted by swirlingcellulosic fibers having a moisture content of from 0 to 150% in astream of air or steam and spraying on glue solution (a), (b) or (c).11. A process as claimed in claim 1, wherein compressing of the gluedcellulosic fibers is performed by producing a fiber mat by scatteringthe glued cellulosic fibers onto a support and compressing said mat to apanel at temperatures of from 80 to 250° C. under pressures of from 5 to50 bar.
 12. A process as claimed in claim 1, wherein further topolyamine (P) or amino resin (b) or (c) the aqueous glue solutioncomprises paraffin wax.
 13. A process as claimed in claim 1, whereinpress tools having a smooth surface are used in step II.
 14. Afiberboard panel comprising cellulosic fibers bound with polyamine (P)alone or with polyamine and with an amino resin (b) or with an aminoresin (c) and having a smooth surface on both sides.
 15. A fiberboardpanel comprising cellulosic fibers bound with polyamine (P) alone orwith polyamine and with an amino resin (b) or with an amino resin (c)and having a density of from 500 to 900 kg/m³ and a thickness of from 6to 40 mm.
 16. An amino resin (c) synthesized from c1) formaldehyde(compound c1); c2) a compound (c2) selected from the group consisting ofurea and melamine, the ratio of the amino groups of compound (c2) toformaldehyde being from 0.1:1 to 2.1; c3) a polyamine P, the molar ratioof the sum of primary, secondary, and tertiary amino groups of polyamineP to the sum of primary amino groups of compound (c2) being from0.0005:1 to 2:1; c4) if desired, up to 0.2 mol per mole formaldehyde ofanother compound, (c4), capable of reacting with formaldehyde in apolycondensation reaction; c5) and, if desired, up to 0.2 mol per moleamino groups of compound (c2) of another compound, (c5), capable ofreacting with amino groups in a polycondensation reaction; andobtainable by in step 1, reacting an aqueous solution of formaldehyde;amounts of compound (c2) such that the ratio of the amino groups ofcompound (c2) to formaldehyde is from 0.1:1 to 2.0:1; amounts ofpolyamine (P) such that the molar ratio of the sum of the primary,secondary and tertiary amino groups of polyamine (P) to the sum of theprimary amino groups of compound (c2) is from 0.0005:1 to 2:1; and ifdesired, in amounts up to 0.2 mol per mole formaldehyde, of anothercompound (c4); and if desired, in amounts up to 0.2 mol per mole aminogroups of compound (c2), a compound (c5) at a pH of from 2.5 to 8.5 anda temperature of from 50 to 100° C. until the solution has a viscosityof from 10 to 2000 mPas (measured at 20° C. on a solution having asolids content of 40%), and in step 2, where necessary, raising the pHto from 6 to 9 and, where necessary, adding urea in amounts such as togive the desired molar ratio of components (c1), (c2), (c3) and (c4) inthe end product, and continuing to react the reaction mixture at atemperature of from 20 to 100° C. until the solution has a viscosity offrom 20 to 2000 mPas (measured at 20° C. on a solution having a solidscontent of 40%).
 17. A process as claimed in claim 6, wherein the aminoresin (c) is obtained by in step 1, reacting an aqueous solution offormaldehyde; amounts of compound (c2) such that the ratio of the aminogroups of compound (c2) to formaldehyde is from 0.1:1 to 2.0:1; amountsof polyamine P such that the molar ratio of the sum of the primary,secondary and tertiary amino groups of polyamine P to the sum of theprimary amino groups of compound (c2) is from 0.0005:1 to 2:1; and ifdesired, up to 0.2 mol per mole formaldehyde of another compound (c4),if desired, in amounts up to 0.2 mol per mole amino groups of compound(c2), another compound (c5) at a pH of from 2.5 to 8.5 and a temperatureof from 50 to 100° C. until the solution has a viscosity of from 10 to2000 mPas (measured at 20° C. on a solution having a solids content of40%), and in step 2, where necessary, raising the pH to from 6 to 9 and,where necessary, adding urea in amounts such as to give the desiredmolar ratio of components (c1), (c2), (c3) and (c4) in the end product,and continuing to react the reaction mixture at a temperature of from 20to 100° C. until the solution has a viscosity of from 10 to 2000 mPas(measured at 20° C. on a solution having a solids content of 40%).
 18. Aprocess as claimed in claim 8, wherein said wood fibers are thoseobtained by hydrothermally pulping woodchips and then defibering them.19. An amino resin (c) as claimed in claim 16, wherein the amino resin(c) is obtained by in step 1, reacting an aqueous solution offormaldehyde; amounts of compound (c2) such that the ratio of the aminogroups of compound (c2) to formaldehyde is from 0.1:1 to 2.0:1; amountsof polyamine (P) such that the molar ratio of the sum of the primary,secondary and tertiary amino groups of polyamine (P) to the sum of theprimary amino groups of compound (c2) is from 0.0005:1 to 2:1; and ifdesired, in amounts up to 0.2 mol per mole formaldehyde, of anothercompound (c4); and if desired, in amounts up to 0.2 mol per mole aminogroups of compound (c2), a compound (c5) at a pH of from 2.5 to 8.5 anda temperature of from 50 to 100° C. until the solution has a viscosityof from 10 to 2000 mPas (measured at 20° C. on a solution having asolids content of 40%), and in step 2, where necessary, raising the pHto from 6 to 9 and, where necessary, adding urea in amounts such as togive the desired molar ratio of components (c1), (c2), (c3) and (c4) inthe end product, and continuing to react the reaction mixture at atemperature of from 20 to 100° C. until the solution has a viscosity offrom 20 to 2000 mPas (measured at 20° C. on a solution having a solidscontent of 40%).